x86: baytrail: Conditionally report S3 in the ACPI table

When U-Boot is built without ACPI S3 support, it should not report
S3 in the ACPI table otherwise when kernel does STR it won't work.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Stefan Roese <sr@denx.de>